Extending the Observational Frequency Range for Gravitational Waves in a Pulsar Timing Array

We provide an observation method for gravitational waves using a pulsar timing array to extend the observational frequency range up rotational of pulsars. For this purpose, we perform analysis perturbed electromagnetic wave in spacetime from field perspective. apply received radio telescope, which partially composes periodic pulse emitted by pulsar. simple observation, two windows are considered. each window, propose gauge-invariant quantities and discuss their observations.